kidneys

Question 1

kidneys description

Answer 1

• pair of reddish brown organs attached to back of abdominal cavity
• surrounded by thick, protective layer of fat and layer of fibrous connective tissue
• involved in excretion and osmoregulation
• filter nitrogenous waste products out of blood, especially urea
• maintain water balance and pH of blood and tissue fluid

Question 2

kidney anatomy

Answer 2

• supplied with blood by renal arteries
• blood removed by renal vein which drains into inferior vena cava
• made up of millions of small nephrons which act as filtering units
• urine is produced by kidney tubules
• urine passes out of kidneys through ureters
• collects in bladder and passes out through urethra

Question 3

kidney cortex

Answer 3

• dark outer layer
• where filtering of blood takes place
• dense capillary network
• carries blood from renal artery to nephrons

Question 4

kidney medulla

Answer 4

• lighter
• contains tubules of nephrons that form pyramids of the kidney and the collecting ducts

Question 5

kidney pelvis

Answer 5

central chamber where urine collects before passing down ureter

Question 6

Bowman’s capsule

Answer 6

• cup-shaped structure
• contains glomerulus which is tangle of capillaries
• more blood goes into glomerulus through afferent arteriole that leaves through efferent arteriole due to ultrafiltration

Question 7

proximal convoluted tube

Answer 7

• first coiled region of tubule after Bowman’s capsule
• in cortex
• where many substances needed by the body are reabsorbed back into blood
• most reabsorption of water takes place

Question 8

loop of Henle

Answer 8

• long loop of tubule
• creates region with very high solute concentration in tissue fluid
• in medulla
• descending limb runs down from cortex to medulla to bend
• ascending limb travels back up through medulla to cortex

Question 9

distal convoluted tube

Answer 9

• second twisted tubule where fine-tuning of water balance of body takes place
• permeability of walls varies in response to levels of ADH in blood
• regulation of ion balance and pH of blood takes place

Question 10

collecting duct

Answer 10

• urine passes down collecting duct through medulla of pelvis
• fine-tuning of water balance takes place as walls are sensitive of ADH

Question 11

blood content of kidneys after it leaves

Answer 11

• reduced levels of urea
• glucose and amino acids the same
• mineral ion concentration restored to ideal levels

Question 12

ultrafiltration

Answer 12

• glomerulus is supplied with blood by relatively wide afferent arteriole from renal artery
• blood leaves through narrower efferent arteriole
• so there is considerable pressure in glomerulus
• this forces blood out through capillary wall
• fluid passes through basement membrane- most the plasma contents apart from RBCs and proteins due to their size
• filtrate which enters capsule contains glucose, salt, urea, others in same concentrations as in blood plasma

Question 13

basement membrane

Answer 13

made up of network of collagen fibres and proteins that make up a second sieve

Question 14

podocytes

Answer 14

• special cells in walls of Bowman’s capsule
• act as additional filter
• have extension called pedicels that wrap around capillaries
• forming slits that make sure any cells, platelets, large plasma proteins that have manged to get through epithelial cells and basement membrane do not get through into the tubule itself

Question 15

glomerular filtration rate

Answer 15

volume of blood filtered through the kidneys in a given time